Up until now the analysis of oxalate in biological fluids has been difficult and time-consuming. The other chemicals present in the fluids interfere with oxalate determination. As a result, it was necessary to separate the oxalate by using a precipitant, by passing the fluid through an ion exchange resin, or by some other technique. The isolated oxalate could then be quantified by using one of several known techniques. These isolation techniques, due to the several steps involved, introduced experimental error that affected accuracy of the results.
Other techniques have attempted to avoid separation of oxalate, by such means as creation of a "blank" to compensate for the other chemicals present. These techniques have not been successful in compensating for contaminants, and results have been inaccurate.